A well known technique for improving the reception of single sideband (SSB) amplitude modulated radio signals is to include a pilot carrier within the transmitted radio signal. The pilot carrier allows the receiver to more reliably determine the carrier frequency of the transmitted signal and can also be used to establish a reference magnitude and phase of the transmitted signal. This technique is used, for example, in the InFLEXion.TM. paging system, which is described in U.S. Pat. No. 5,689,440 entitled "Voice Compression Method and Apparatus in a Communication System" issued to Leitch et al. on Nov. 18, 1997, in which a plurality of independent SSB modulated analog signals (which are typically voice signals) can be simultaneously transmitted. In the InFLEXion.TM. paging system, the independent SSB analog signals are time compressed and digitally transformed analog signals that are modulated in pairs, each pair being modulated about a pilot carrier. In SSB systems, the ratio of the average power of the signal to the pilot carrier power needs to be maintained at a constant level with very minimal variation so as to achieve good quality transmission and reception. Since it is not difficult to maintain the pilot signal precisely by prior art techniques, maintenance of the ratio is accomplished by acquiring and maintaining a gain of the analog signal during an analog message, such as a voice message. A precision maintenance of this ratio, such as a maximum variation of .+-.0.5 dB (decibels) during a single voice message, is at least as important in the InFLEXion.TM. paging system as in other SSB systems, and can improve the quality of the received signal several fold over signals having less well regulated ratios, such as the ratios provided by commonly used standard automatic gain control circuits, which typically vary by at least a couple of dB. Maintaining the ratio is made more complex in a paging system than in some other systems by the fact that the analog signals are voice messages (in contrast, for example, to a system in which only modem signals are transmitted), and they are typically generated by a variety of sources, such as different telephone instruments and other voice transducers, and the fact that received voice signals are subject to large variation in amplitude (&gt;40 dB) due to different connections or path losses in the public telephone network.
Thus, what is needed is an improved technique for precisely controlling the ratio of the signal level of a SSB single sideband signal to a pilot carrier during an analog signal that carries voice messages.